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Children of Smokers Carry Tobacco Toxins on Their Hands

Medpage Today

By Salynn Boyles

Children of smokers routinely carried nicotine on their hands, indicating that exposure to thirdhand smoke appears to play an important role in overall tobacco exposures among young children whose parents smoke cigarettes, according to researchers.

In the pilot study, children of smokers with exposures to secondhand smoke had higher than expected levels of nicotine on their hands, implying exposure to thirdhand smoke as well, reported E. Melinda Mahabee-Gittens, MD, of Cincinnati Children’s Hospital Medical Center, and colleagues.

The finding of a significant association between hand nicotine and salivary cotinine, which is a biomarker of systemic tobacco exposure, suggests that thirdhand smoke exposure may contribute to overall tobacco exposure in children, independent of exposure to secondhand smoke, they wrote in Tobacco Control.

“The nicotine levels on the hands of children in our study were exceptionally high,” Mahabee-Gittens told MedPage Today, adding that these levels tended to be significantly higher than those previously reported in non-smoking adults.

Breathing secondhand smoke exhaled by smokers has been shown in numerous studies to pose significant health risks to young children, but the impact of exposure to smoke residues left on dust and surfaces — known as thirdhand smoke — on children’s health is not known. However, dust and surfaces have been shown to be important sources of lead and pesticide exposure in young children.

The study enrolled 25 children (mean age 5.4 years) who presented to a single emergency department (ED) from April to September of 2016 with a potentially secondhand smoke-related illness. All the children had a parent who smoked and were considered at risk for smoke exposures.

The children provided saliva samples, which were analyzed for cotinine. The palm and fingers of their dominant hands were wiped by trained research staffers and analyzed for nicotine.

One child had a nicotine level of close to 691 ng/wipe, which was higher than the level expected in an active smoker.

“Our findings indicate that children carry tobacco smoke toxicants on their hands, even when nobody around them is smoking,” the researchers wrote. “Thus, nicotine and other thirdhand smoke compounds on children’s hands may contribute to overall tobacco smoke (exposure), independent of secondhand smoke.”They added that because nicotine is specific to tobacco, its presence on children’s hands may serve as a proxy of tobacco smoke pollution in their immediate environment.

“This finding suggests that overall tobacco smoke may occur through a combination of secondhand smoke and thirdhand smoke exposure via multiple pathways; thus, a comprehensive assessment of overall tobacco smoke needs to include assessments of both secondhand smoke and thirdhand smoke exposures.”

The researchers noted that hand wipe testing may be feasible and useful in the clinical setting.

Mahabee-Gittens told MedPage Today that the impact of thirdhand smoke exposure on the health of children is not yet known. The researchers hope to study this in a much larger secondhand and thirdhand smoke exposure study.

Study limitations included its small sample size and inability to determine how secondhand and thirdhand smoke exposures contribute to overall exposures.

Still, Mahabee-Gittens said the findings have important clinical implications.

“Parents who smoke may think they are protecting their children by not smoking around them,” she said. “This study suggests that there still may be harms. Even if parents smoke outside it is likely that they are bringing tobacco contaminants and pollution back into the home when they come inside.”